There are a variety of base configurations for biaxially stretched blow molded PET containers on the market. These include configurations, for example described in U.S. Pat. No. 4,785,949 and U.K. Patent Application No. 2067160. The former (see FIGS. 5 and 6) comprises a central convex portion and five radiating legs, and is characterized in that the legs and feet are generally of the same outline as the ribs and legs of a base configuration having six legs and feet, thereby rendering the ribs between the feet greater width. The latter (see FIGS. 7 and 8) disclose a base configuration with a concave central portion formed therein, the periphery of the concave central portion intersecting a lower end of an inclined rim. However, stress cracks or even rupture is initiated in such base configurations when the applied pressure exceeds a certain critical level.
Therefore it is an object of the present invention to provide a base configuration for biaxially stretched blow molded PET containers which may obviate and mitigate the above-mentioned drawbacks.